Electronic device, electronic device system control method and electronic device system

ABSTRACT

An electronic device connected to a network corresponding to plug &amp; play and hot plug functions and enabled to control other electronic devices is provided with communication route detecting unit for detecting a communication route between electronic devices being used or reserved for communication and notifying unit for notifying the user of a result of detection by the communication route detecting unit. The above-described electronic device is configured so as to detect a communication route between subject electronic devices to be used for communication and notify the user of the electronic devices on the communication route, which must not be disconnected from the network with use of the communication unit. Consequently, the user can be prevented from accidental disconnection of the cable of a subject electronic device, thereby preventing the disconnection of the device from the network.

TECHNICAL FIELD

The present invention relates to an information-related home electricappliance enabled to construct a network corresponding to play & plugand hot plug functions via a digital interface regulated by theIEEE1394, etc. More particularly, the present invention relates to adevice for controlling other devices remotely and managing states ofdata transfer with and among those devices in communications.

BACKGROUND ART

Now that personal computers are used widely in general homes for thepurpose of doing various operations, such as accessing the Internet, theword of “network” is becoming very familiar to general users. Inaddition, there have appeared various digital information-related homeappliances such as digital video cassette recorders, digital videocameras, etc., so that users can construct even intra-home networkseasily in their homes now, since those appliances are provided with anIEEE1394 interface respectively. On the contrary, the IEEE1394 standard,expecting on the basis of the experience from the SCSI bus that thestandard will be used by those general users more and more, has realizeda plug & play function for assigning an ID to a device automatically soas to construct such an intra-home network just by connecting the deviceto a network, as well as a hot plug function for enabling the device tobe disconnected/connected from/to the network while the device ispowered. The IEEE1394 standard has also enabled devices to be connectedat higher freedom, for example, by any of the daisy chain method and thenode branching method. Both methods can also be used together.

The plug & play AV system disclosed in JP-A-116819/1997, givingconsideration to unskilled users, uses a digital interface that candetect each newly connected/disconnected AV device so as to enablevarious required settings to be made and the set items to be displayedautomatically. Consequently, when the cable of an AV device isdisconnected, a warning message is displayed so that the user can knowwhich device is disconnected.

The above-described conventional technique, however, displays such awarning message after the cable disconnection, so it cannot prevent suchan accidental case where a program the user has watched is shut down dueto the disconnection of the AV device cable, thereby the device isdisconnected from the network.

DISCLOSURE OF THE INVENTION

Under such circumstances, it is an object of the present invention toprevent such an accident that the user disconnects a device cable,thereby the device is disconnected from a network by notifying the userof the devices that must not be disconnected from the networkbeforehand.

In order to achieve the above object, the present invention provides atechnique for providing each electronic device connected to a networkwith connection information storing means for storing connectioninformation of an interface port of the electronic device.

At least one (controller) of the electronic devices connected to thenetwork is provided with means for controlling other devices so as tocontrol them remotely via the network and transfer data to those devicesvia the device (controller). The device (controller) is further providedwith communication route detecting means for detecting a communicationroute between devices being used or reserved for communication andnotifying means for notifying the user of a communication route detectedby the communication route detecting means. Hereinafter, the deviceprovided with the functions will be referred to as a controller.

The controller composed and connected to a network as described above,when in communication with any of other devices, requests all of thoseother devices for connection information so as to detect thecommunication route between subject devices with use of the receivedconnection information. The controller then notifies the user that thedevices connected to the detected communication route must not bedisconnected from the network.

Consequently, the user can prevent an accidental disconnection of acable from a device that must not be disconnected from a network duringcommunication, thereby preventing disconnecting of the device from thenetwork.

Furthermore, the controller is provided with disconnection detectingmeans for detecting disconnection from a communication route detected bythe communication route detecting means so that notifying means notifiesthe user of a disconnected portion when the disconnection detectingmeans detects disconnection from the communication route.

Because a disconnected point of the communication route is notified tothe user such way, the user can recover the communication route fromdisconnection immediately.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a network system of the present invention.

FIG. 2 is a simplified circuit diagram of a controller in an embodiment(first embodiment) of the present invention.

FIG. 3 is a flowchart for processings of the controller in an embodiment(first embodiment) of the present invention.

FIG. 4 is a flowchart for the initialization of an IEEE1394 serial busexecuted in accordance with the IEEE1394 standard.

FIG. 5 is a configuration of connection information.

FIG. 6 is an example of a topology map of the network system of thepresent invention.

FIG. 7 is a configuration of network connection information.

FIG. 8 is a flowchart for a communication route detecting algorithm usedfor between a source device and the controller.

FIG. 9 is a notifying method used for a user.

FIG. 10 is a circuit diagram of a controlled device.

FIG. 11 is a flowchart for processings of the controller in anotherembodiment (second embodiment) of the present invention.

FIG. 12 is a simplified circuit diagram of the controller in stillanother embodiment (third embodiment) of the present invention.

FIG. 13 is a flowchart for the processings of the controller in stillanother embodiment (third embodiment) of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereunder, the preferred embodiments of the present invention will bedescribed with reference to the accompanying drawings.

FIG. 1 shows a block diagram of a network system of the presentinvention. The network system is connected to a digital TV (hereinafter,to be described as the “D-TV”) 101 enabled to receive and displaydigital image signals; a personal computer (hereinafter, to be describedas the “PC”) 102; digital satellite broadcasting receiver (hereinafter,to be described as the “IRD”) 103; a digital video cassette recorder(hereinafter, to be described as the “D-VCR”) 104; a digital videocamera (hereinafter, to be described as the “D-CAM”) 105; and a printer106 via the digital interface port of each electronic device and cables111, 112, 113, 114, and 115.

In this embodiment, it is assumed that each of the interfaces betweenthe cables 111 to 115 and devices corresponds to the plug & playfunction that updates the network automatically, as well as the hot plugfunction that enables electronic devices to be connected/disconnectedto/from the network while they are powered, and that each of theinterfaces is such a bus interface as the IEEE1394 serial bus, whichemploys a protocol for recognizing whether or not the correspondingdigital interface port is connected by means of the ID number, theaddress, etc. The interface is not limited only to the IEEE1394 serialbus, of course; the digital interface may be a USB (Universal SerialBus).

Furthermore, in this embodiment, at least one of the electronic devicesconnected to the network is provided with a function for controllingother electronic devices and communications between the electronicdevices connected to the network are done under the control of thisdevice. Hereinafter, an electronic device provided with this functionwill be referred to as a controller. The rest electronic devicescontrolled by the controller will be referred to as controlled devices.The communication between those controlled devices means communicationof such stream data as MPEG (Motion Picture Experts Group), etc.

In this embodiment, it is assumed that the IRD 103 is a controller andthe rest devices are controlled devices. The rest devices may becontrollers, of course.

The control protocol used by the controller for controlling controlleddevices may be a method in which each controlled device uproads aprogram regulated by, for example, the HAVi (Home Video/Videointeroperability) and used to control controlled devices to thecontroller and the controller controls the controlled devices with useof the program. The control protocol may also be a method regulated bythe CEBus (Consumer Electronics Bus) that employs a regulated protocolfor sending predetermined control commands to the controlled devices.

FIG. 2 shows a simplified circuit diagram of the IRD 103, which is acontroller. The reference numeral 201 denotes a bus of the CPU 202 ofthe IRD 103. The bus 201 is used to exchange data between the IRD 103and each controlled device. The reference numeral 203 denotes a digitalinterface. The reference numeral 204 denotes connection informationstoring means for holding a device ID specific to each electronicdevice, a node ID, the number of interface ports provided for theelectronic device, and each port connection information. The referencenumeral 205 denotes connection state storing means for storingconnection information of each electronic device connected to a networkand connection information of each electronic device connected to thenetwork. The reference numeral 206 is communication route detectingmeans for detecting a communication route between electronic devicesbeing used or reserved for communication with use of the connectioninformation of electronic devices held in the connection state storingmeans. The reference numeral 208 denotes notifying means for notifyingthe user of a communication route detected by the communication routedetecting means. The reference numeral 209 denotes control storing meansfor storing programs and data used to control controlled devices.

It is assumed here that each of the D-TV 101, the PC 102, the D-VCR 104,the D-CAM 105, and the printer 106 connected to a network is provided atleast with devices equivalent to the digital interface 203 and theconnection information storing means 204 shown in the circuit diagram ofthe IRD 103 in FIG. 2.

Hereunder, the first embodiment will be described in detail withreference to the accompanying drawings.

FIG. 3 shows a flowchart for processings of the controller in this firstembodiment of the present invention to so as to prevent an accidentaldisconnection of a device from a network during an operation.

When an electronic device is connected to a network or when theelectronic device is powered, a bus reset signal is generated, therebythe digital interface is initialized and a node ID is decided for eachconnected device (step 301). Then, the controller generates connectioninformation for denoting the connection state of each port of theelectronic device and stores the connection information in theconnection information storing means 204 (step 302). Ending theinitialization of the digital interface, the controller requests eachcontrolled device for the connection information and stores the receivedconnection information in the connection state storing means 205 (step303). The controller monitors the communication request event or thecommunication reservation event between connected controlled devices instep 304. When a communication transfer request or communicationreservation event is generated, the event becomes a trigger for thecommunication route detecting means 206 to detect a communication routebetween subject controlled devices (step 305). Ending the detection ofthe communication route, the controller notifies the user of thecontrolled devices that must not be disconnected from the communicationroute (step 306).

Next, a description will be made for the processing in each step indetail.

(1) Initialization of Digital Interface (Step 301)

As described above in this first embodiment, the digital interface isassumed as an IEEE1394 serial bus. Hereinafter, therefore, theinitialization procedure in accordance with the IEEE1394 serial standardwill be described. FIG. 4 shows a flowchart for the initializationexecuted in accordance with the IEEE1394 serial bus standard.

When a node is connected to a network or the node is powered, a busreset signal is generated, thereby the bus initialization in step 401 isstarted for the controlled device. In the initialization processing, thecontroller erases the topology-related information of the node andidentifies whether the node connection type is “branch” in which theconnection is done to two or more nodes or “leaf” in which theconnection is done to only one node or the interface is completelyisolated; the connection is not done to any node.

Next, control goes to the tree identification processing (in step 402).

In this tree identification processing, at first, each “leaf” nodedeclares a parent and child relationship to a higher node sequentiallyand each “branch” node declares a parent and child relationship to ahigher node sequentially (step 403). This processing is done for everynode (step 404). Finally, a node assumed as the parent for all theconnected ports becomes a “route node” (step 405).

When a “route node” is decided and the tree identification is ended,control goes to a self-identification processing (step 406).

In this self-identification processing, a node ID is set for each nodesequentially, beginning at a leaf node positioned at the bottom of thetree structure (step 407). A node, when a node ID is set thereto,broadcasts its ID packet to other nodes so as to report the self node ID(step 408). A self-node ID is decided so that “0” is set for the node IDof a leaf node positioned at the bottom of the tree structure. This nodebroadcasts its node ID=0 to other nodes. This operation is repeatedsequentially until the self node ID=1,2 . . . is reached.

The initialization of the digital interface is completed when it iscompleted to decide an ID for every node (step 409).

The self ID packet to be broadcast includes the self-node ID, the numberof ports owned by the node, the number of ports connected to a network,information of the parent/child relationship of each port, etc.

(2) Generation of Connection Information (Step 302)

Hereinafter, a description will be made for a method for generatingconnection information. When a subject electronic device connected to anetwork is a “leaf” one, the connection information consists of a deviceID specific to the device, a node ID, and port information including thenumber of ports owned by the device and the connection state of each ofthe ports. When the subject electronic device connected to a network isa “branch” one, the connection information consists of the connectioninformation of the “leaf” device+the node ID information of eachelectronic device connected to each port. A device ID is equivalent to aunique vender ID stored in a configuration ROM, which is used worldwideso as to recognize each device when the device conforms to the IEEE1394standard. The port information, as described above, is equivalent to theinformation included in each self ID packet generated when the digitalinterface is initialized. The node ID of each electronic deviceconnected to each port is obtained by extracting the node ID from theself ID information broadcast in the initialization processing of thedigital interface. A branch device, when receiving the self IDinformation of a child device, that is, an electronic device connectedto a port, obtains the node ID of the connected device by extracting thenode ID therefrom.

FIG. 5 shows a configuration of connection information when aparent/child relationship and a node ID are decided for a device asshown in FIG. 6 after the initialization of a digital interface. In FIG.5, each data name is written in thick letters and each data is writtenin normal letters. FIG. 5(a) shows an example of connection informationof the IRD 103 and FIG. 5(b) shows an example of the connectioninformation of the D-VCR 104. In FIG. 6, the correspondence between eachdevice and its device ID is decided as follows; D-TV 101=101, PC102=102, IRD 103=103, D-VCR 104=104, D-CAM 105=105, and printer 106=106.The correspondence between each device and its node ID is decided asfollows; D-TV 101=1, PC 102=4, IRD 103=5, D-VCR 104=3, D-CAM 105=0, andprinter 106=2. In FIG. 6, “p” denotes that a parent device is connectedto the port and “c” denotes that a child device is connected to theport.

In FIG. 5, port connection information denotes whether or not anelectronic device is connected to a subject port. P0 and P1 denote port1 and port 2 respectively. Data “11′ denotes that the port is connectedto a child device and “10” denotes that the port is connected to aparent device. “01” denotes that nothing is connected to the port. Thedestination information is a node ID of an electronic device connectedto the port. In FIG. 6, the device name is also described for easierunderstanding. Text information denoting each device name may be storedtogether with its node ID such way. The destination information recordsonly the information of the ports connected to child devices inascending order of port numbers. The connection information can beprevented from duplication when each electronic device describes onlythe connection information of child devices.

(3) Storing Connection Information (Step 303)

The controller requests each controlled device connected to a networkfor the connection information so as to generate the network connectionstate information of the network and stores the information in theconnection state storing means 205. FIG. 7 shows a configuration of theconnection state information. In FIG. 7, each data name is written inthick letters and each data is written in normal letters. Eachconnection state information may include connection information of everycontrolled device connected to the subject network. In this embodiment,however, the connection state information includes the connection statesof only branch devices. This is because each leaf device is alwaysconnected to any one of branch devices, so that it is possible to obtainthe connection state information of the whole network only from theconnection information of branch devices.

Each connection state information consists of a device ID, a node ID,the number of ports, and each port connection information. Each portconnection information consists of the connection state of each port, aswell as the node ID and the device ID of each destination device. Asshown in FIG. 7, text information denoting a device name may be storedtogether with a device ID.

(4) Monitoring a Communication Request (Step 304)

In this embodiment, the controller can control controlled devices andthe user can control all the devices connected to a subject network viathis controller. Therefore, the controller can manage all the states ofthe controlled devices connected to the network, so that the controllercan recognize each communication request issued from a controlled deviceto another.

When the controller detects such a communication request orcommunication reservation request issued from a controlled device toanother, control goes to a step for communication route detection.

(5) Detection of a Communication Route (Step 305)

A communication route is detected in two phases in this embodiment; aroute between a source device that sends data and the controller isdetected in one phase and a route between a sink device that receivesdata and the controller is detected in the other phase.

FIG. 8 shows a flowchart for a route detection algorithm for detecting acommunication route from a source device to the controller.

A communication route from a source device to the controller is detectedas follows. At first, the controller is searched from the source devicetowards the route device, then the route is searched from the sourcedevice side (step 800). When the controller cannot be found in thesearch up to the route device, the searching is then done from thecontroller side (step 810) so as to search the controlled devices on theroute from the source device towards the controller.

Hereinafter, a description will be made for the communication routedetection algorithm employed for the route searching from a sourcedevice to the controller with reference to the flowchart shown in FIG.8.

At first, a target device is set as a source device and the number ofdevices on the route is set to 0 (initialization). Then, the system goesto step 802 so as to refer to the connection state information andchecks whether or not the controller is connected to a port of thetarget device. When the controller is connected, the source device andthe controller are connected to each other directly. The system thusexits the processing. When the controller is not connected to any portof the target device, the system increases the number of devices on theroute and adds the target device ID to the device IDs of the devices onthe route (step 804). When the target device is a route device at thistime, the system begins searching of the source device from thecontroller side (step 810). When the target device is not a routedevice, the system sets the parent device of the target device as thetarget device (step 805), then repeats the processings in steps 802 to803.

The searching of the source device from the controller side (step 810)is also done in the same way as the communication route detection fromthe source device to the controller. The communication route detectionfrom the controller side is ended when the source device and acontrolled device among those on the route of the route device aredetected.

After that, the detected communication route from the source device tothe route device is combined with the communication route detected fromthe controller side so as to generate device information of thecommunication route from the source device to the controller (step 806).The communication route detection from the sink device to the controlleris also done in the same procedure as that of the communication routedetection from the source device to the controller as described above.The above two communication route detection results (the detectedcommunication route from the sink device to the controller and thedetected communication route from the source device to the controller)are combined so as to generate information of the communication routefrom the source device to the sink device.

(6) Notification to the User (Step 306)

When the information of the communication route from the sink device tothe source device is generated as described above, the system notifiesthe user of the devices that cannot be disconnected from thecommunication route with use of the generated information.

In case where the user watches a movie played back by the D-VCR 104 onthe D-TV 101 via a network as shown in FIG. 6 at this time, the routefrom the source device to the sink device includes the D-VCR 104, theIRD 103, the PC 102, and the D-TV 101.

FIG. 9 shows a method for notifying a user of the devices that cannot bedisconnected from a network. The reference numeral 901 denotes such anotifying means as a liquid crystal panel provided for the controller.The notifying means displays how the current network is used, as well asthe names of the electronic devices on a subject communication route.The system thus notifies the user of the electronic device used by theuser at that time, as well as other electronic devices on the route thatcannot be disconnected from the network. Although the warning message isrepresented as a text in this embodiment, the message may be representedgraphically, for example, as icons, etc. for denoting those electronicdevices.

As described above, according to the present invention, a communicationroute between subject devices is detected and the user is notified ofthe devices that cannot be disconnected from the network before startingthe communication between the devices. Thus, the user is protected fromaccidental disconnection of the necessary devices from the network. Thisis an effect of the present invention.

While the warning message is displayed on the display means provided forthe controller in the this embodiment, it is also possible to send anddisplay the warning message on the screen of the D-TV 101/the PC 102provided for the subject electronic device. This is another effect ofthe present invention.

When the controller is provided with means for making a sound, means foremitting or blinking a light so as to output a warning sound or light orboth of them and attract the user's attention and prevent the user fromaccidental disconnection of necessary devices from the network, theabove effects will be improved more.

Next, the second embodiment of the present invention will be described.Also in this second embodiment, the network configuration shown in FIG.6 is employed. The configuration of the IRD 103, which is a controller,is the same as that shown in FIG. 2. FIG. 10 shows a circuit diagram ofa controlled device connected to the controller. The circuit diagrams ofthe digital interface 203 and the connection information storing means204 are the same as those shown in FIG. 2. The reference numeral 10-1denotes a circuit for controlling functions specific to each electronicdevice. The reference numeral 10-3 denotes communication route flagstoring means for storing a communication route flag for denoting thatthe flag-set electronic device is on the subject communication route.The reference numeral 10-2 denotes notifying means for notifying theuser of the electronic devices that cannot be disconnected from thesubject communication route.

FIG. 11 shows a flowchart for the processings of the controller in thesecond embodiment of the present invention so as to protect the userfrom accidental disconnection of necessary electronic devices on acommunication route from a network. In FIG. 11, the same step numberswill be used for the same processings as those shown in FIG. 3. In thissecond embodiment, the processings up to the notification to the user(step 306) are the same as those in the flowchart shown in FIG. 3 in thefirst embodiment. After the notification, the controller sends data usedto set a communication route flag to each electronic device on thecommunication route and used for the communication (step 11-1). When thecommunication ends (step 11-2), the controller sends data used to resetthe communication route flag to each of the flag-set electronic devices.

Each flag-set electronic device on the communication route is set isnotified to the user by the notifying means 10-3. In case where thecable of an electronic device is disconnected while the communicationroute flag is set therein, the notifying means 10-3 notifies the user ofthe disconnection from the network.

For example, the electronic device is provided with an LED on the frontpanel so that the LED comes on when the communication route flag is settherein and the LED goes off when the flag is reset. When the cable ofan electronic device is disconnected while the communication route flagis set therein, the LED blinks. Such way, the notifying means 10-3notifies the user of the state of each electronic device by such an LEDwhose state is varied among the states of the device.

The notifying method may use any of a sound, a light, and blinking of alight, or a combination of those items. In case where an electronicdevice is provided with such means as a liquid crystal panel, etc. thatcan represent the states thereof with characters and graphic patterns,the warning (notification to the user) may be represented by thosecharacters and graphic patterns.

In this second embodiment, because the user is notified of each deviceused on the subject communication route by the device itself, as well asby the controller, the user is prevented from accidental disconnectionof the necessary devices from the network more effectively.

Next, the third embodiment of the present invention will be describedwith reference to the accompanying drawings. Also in this thirdembodiment, the network configuration shown in FIG. 6 is employed. FIG.12 shows a block diagram of the controller in this third embodiment. InFIG. 12, the same numbers are used for the same components as thoseshown in FIG. 2. The reference numeral 207 denotes disconnectiondetecting means for detecting disconnection of a communication routedetected by the communication route detecting means. The controlleddevices connected to the route are the same as those shown in FIG. 10.FIG. 13 shows a flowchart for the processings of the controller in thisthird embodiment of the present invention. Hereinafter, the processingsof the controller will be described with reference to the flowchartshown in FIG. 13. In FIG. 13, the same step numbers are used for thesame processings as those in the flowcharts shown in FIGS. 3 and 11. Theprocessings up to the notification to the user of a communication routeare the same as those described with reference to FIG. 3.

When disconnection of a communication route is detected, a bus resetevent always occurs. Such a bus reset event also occurs when a newelectronic device is connected to a network while the communicationroute is not disconnected or even when an electronic device that is noton the communication route is disconnected from the network. In anycase, the digital interface is initialized (step 301) just like in theprocessing described with reference to FIG. 3 and the connectioninformation is generated (step 302). After that, the controller requestseach connected electronic device for the connection information andupdates the connection state information (step 12-1). The disconnectiondetecting means thus refers to the device ID information in theconnection state information so as to check whether or not there is anydevice on the route, thereby detecting the disconnection of thecommunication route (step 12-2). For the detection of communicationroute disconnection, a device ID is used, since the node ID is possiblychanged at each initialization of the digital interface. When thecommunication route is not disconnected, the system continues thecommunication (step 12-3). When disconnection of the communication routeis detected, the system notifies the user of the disconnection anddisplays the name of any electronic device disappeared from the networkso as to instruct the user to connect the electronic device to thenetwork again (step 12-4). The system then sets a timeout time to becounted until the communication is abandoned to a proper value, forexample, 30 sec (step 12-5). When a timeout occurs, the system abandonsthe communication (step 12-7) and notifies the user of the abandon (step12-8). In case where a bus reset event occurs again before the timeout,the system repeats the processings from the initialization of thedigital interface to the detection of the communication routedisconnection (step 12-2). When no communication route disconnection isdetected at this time, the communication is continued.

When an electronic device is disconnected from a network duringcommunication such way, the disconnection is notified to the user andthe user is requested to connect the device to the network again. Thecommunication is thus continued.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, the controllerconnected to a network requests each of the devices connected to thenetwork for the connection information before starting communicationbetween subject electronic devices so as to detect a communication routebetween those electronic devices with use of the received connectioninformation. The controller sends a warning message to the user so asnot to disconnect each necessary electronic device from the detectedcommunication route via the notifying means.

Consequently, the user is protected from accidental disconnection of thenecessary devices from the network beforehand.

Furthermore, when the controller is provided with disconnectiondetecting means for detecting disconnection of a communication routedetected by the communication route detecting means and thedisconnection detecting means detects disconnection of a subjectcommunication route, then the controller notifies the user of thedisconnected point via the notifying means.

Consequently, when a disconnected point of a communication route isnotified to the user, the user can connect the communication route againimmediately.

[DOCUMENT NAME] DRAWING

[FIG. 1]

-   106 . . . PRINTER

[FIG. 2]

-   204 . . . CONNECTION INFORMATION STORING MEANS-   205 . . . CONNECTION STATE STORING MEANS-   206 . . . COMMUNICATION ROUTE DETECTING MEANS-   208 . . . NOTIFYING MEANS-   209 . . . CONTROL STORING MEANS

[FIG. 3]

-   BUS RESET?-   301 . . . INITIALIZE DIGITAL INTERFACE.-   302 . . . GENERATE CONNECTION INFORMATION.-   303 . . . STORE CONNECTION INFORMATION.-   304 . . . COMMUNICATION REQUEST RECEIVED?-   305 . . . DETECT COMMUNICATION ROUTE.-   306 . . . WARNING

[FIG. 4]

-   BUS RESET-   401 . . . INITIALIZE BUS.-   402 . . . TREE IDENTIFICATION-   403 . . . DECLARE PARENT/CHILD RELATIONSHIP.-   404 . . . ALL THE NODES DECLARED?-   405 . . . DECIDE ROOT NODE.-   406 . . . SELF-IDENTIFICATION-   408 . . . BROADCAST ID INFORMATION.-   409 . . . ALL THE NODES DECIDED?

[FIG. 5]

-   (a)-   DEVICE ID-   NODE ID-   NUMBER OF PORTS-   PORT CONNECTION INFORMATION-   DESTINATION INFORMATION-   (b)-   PORT CONNECTION INFORMATION    -   11: CONNECTED TO CHILD DEVICE    -   10: CONNECTED TO PARENT DEVICE    -   01 . . . UNCONNECTED

[FIG. 6]

-   ROOT NODE (103.5)<—DEVICE ID, NODE ID)-   106 . . . PRINTER-   PORT NO.-   p: CONNECTED TO PARENT DEVICE-   c: CONNECTED TO CHILD DEVICE

[FIG. 7]

-   DEVICE ID (DEVICE NAME)-   NODE ID-   NUMBER OF PORTS-   CONNECTION STATE DESTINATION NODE ID DEVICE ID (DEVICE NAME)-   CONNECTION INFORMATION    -   11: CONNECTED TO CHILD DEVICE    -   10: CONNECTED TO PARENT DEVICE    -   01: UNCONNECTED

[FIGURE 8]

-   801 . . . TARGET DEVICE=SOURCE DEVICE DEVICES ON ROUTE Ns=0-   802 . . . CONTROLLER?-   803 . . . DEVICES ON ROUTE Ns++ROUTE DEVICE IDS_ID[Ns]=DEVICE ID-   805 . . . TARGET DEVICE=PARENT DEVICE-   804 . . . ROOT?-   810 . . .-   TARGET DEVICE=CONTROLLER DEVICES ON ROUTE Nr=0-   ROUTE DEVICE?-   ROUTE DEVICE COUNT Nc++ROUTE DEVICE IDC_ID[Ns]=DEVICE ID-   TARGET DEVICE=PARENT DEVICE-   806 . . . GENERATE DEVICE INFORMATION OF COMMUNICATION ROUTE BETWEEN    SOURCE AND CONTROLLER

[FIG. 9]

-   WARNING!!-   D-VCR—>D-TV-   “SENDING A STREAM”-   DO NOT DISCONNECT D-VCR, D-TV, IRD, AND PC FROM THE NETWORK.

[FIG. 10]

-   10-1 . . . DEVICE SPECIFIC CIRCUIT-   204 . . . CONNECTION INFORMATION STORING MEANS-   10-3 . . . NOTIFYING MEANS-   10-2 . . . COMMUNICATION ROUTE FLAG STORING MEANS-   [FIG. 11]-   BUS RESET?-   301 . . . INITIALIZE DIGITAL INTERFACE.-   302 . . . GENERATE SELF INFORMATION.-   303 . . . STORE NETWORK CONNECTION INFORMATION.-   304 . . . DATA TRANSFER REQUESTED?-   305 . . . SEARCH ROUTE.-   306 . . . WARNING-   10-1 . . . COMMUNICATE EACH DEVICE ON COMMUNICATION ROUTE.-   10-2 . . . COMMUNICATION ENDED?-   10-3 . . . COMMUNICATE EACH DEVICE ON COMMUNICATION ROUTE.

[FIG. 12]

-   204 . . . CONNECTION INFORMATION STORING MEANS-   205 . . . CONNECTION STATE STORING MEANS-   206 . . . COMMUNICATION ROUTE DETECTING MEANS-   207 . . . DISCONNECTION DETECTING MEANS-   208 . . . NOTIFYING MEANS-   209 . . . CONTROL STORING MEANS

[FIG. 13]

-   BUS RESET-   301 . . . INITIALIZE DIGITAL INTERFACE.-   302 . . . GENERATE CONNECTION INFORMATION.-   12-1 . . . UPDATE CONNECTION INFORMATION.-   12-2 . . . DETECT DISCONNECTION OF COMMUNICATION ROUTE.-   COMMUNICATION ROUTE DISCONNECTED?-   12-3 . . . CONTINUE COMMUNICATION.-   12-4 . . . WARNING-   12-5 . . . SET TIMEOUT TIME.-   12-6 . . . TIMEOUT?-   12-9 . . . BUS RESET?-   12-7 . . . ABANDON CONTINUATION OF COMMUNICATION.-   12-8 . . . SEND NOTICE.

1. An electronic device (controller) enabled to connect a differentelectronic device so as to control said different electronic deviceremotely, said device (controller), comprising: a communication routedetecting unit for detecting a communication route between said device(controller) and said electronic devices; and notifying unit fornotifying a user of said communication route detected by saidcommunication route detecting unit, said device (controller) configuredto send a flag-set command to one or more electronic devices connectedalong said communication route in order to set a flag that is stored ineach of said one or more electronic devices.
 2. The electronic device(controller) according to claim 1, wherein said communication routedetecting unit requests said one or more electronic devices forconnection information so as to detect said communication route based onsaid connection information.
 3. The electronic device (controller)according to claim 1, wherein said communication route detecting unitdetects said communication route in response to a request for using orreserving one of said one or more electronic devices and notifies theuser of said detected communication route.
 4. The electronic device(controller) according to claim 1, wherein said communication routedetecting unit detects said communication route and notifies the user ofsaid detected communication route when use of said one or moreelectronic devices begins.
 5. The electronic device (controller)according to claim 1, wherein said detected communication route is keptnotified to the user while said one or more electronic devices are beingused.
 6. The electronic device (controller) according to claim 1,wherein notification of said detected communication route is ended whenuse of said one or more electronic devices cease.
 7. The electronicdevice (controller) according to claim 1, wherein said device(controller) sends information used to reset said communication routeflag to said one or more electronic devices when use of saidcommunication route is ended.
 8. The electronic device (controller)according to claim 1, wherein said notifying unit emits or blinks thelight of a corresponding LED for said notification to the user.
 9. Theelectronic device (controller) according to claim 1, wherein saidnotifying unit outputs a corresponding sound for said notification tothe user.
 10. The electronic device (controller) according to claim 1,wherein said notifying unit outputs a warning sound for saidnotification to the user.
 11. The electronic device (controller)according to claim 1, wherein said notifying unit combines any ofmethods for emitting or blinking the light of a LED, as well as foroutputting a corresponding sound or a corresponding warning sound forsaid notification to the user.
 12. The electronic device (controller)according to claim 1, wherein said device (controller) converts awarning message to information corresponding to each of the outputformats of such electronic devices as ones having image display unit,unit for outputting a sound, or both of unit for displaying an image andunit for outputting a sound; and sends said warning message to each ofsaid electronic devices or to a combination of said electronic devices.13. The electronic device according to claim 12, wherein said devicesends connection information to said different electronic device. 14.The electronic device according to claim 12, wherein said device sendsconnection information to said different electronic device in responseto a request therefrom.
 15. An electronic device (controller) enabled toconnect a different electronic device so as to control said differentelectronic device remotely, said (controller) device, comprising: aconnection state storing unit for storing connection information of saiddifferent electronic device; a communication route detecting unit fordetecting a communication route between said device (controller) andsaid electronic device based on said connection information stored insaid connection state storing unit; and a notifying unit for notifying auser of said communication route detected by said communication routedetecting unit, said device (controller) configured to send a flag-setcommand to one or more electronic devices connected along saidcommunication route, in order to set a flag that is stored in each ofsaid one or more electronic devices.
 16. The electronic device(controller) according to claim 15, wherein said connection statestoring unit requests said electronic device connected to a network forthe connection information each time a network reset event occurs so asto update connection information stored in said connection state storingunit.
 17. An electronic device (controller) enabled to connect adifferent electronic device so as to control said different electronicdevice remotely, said device (controller), comprising: a communicationroute detecting unit for detecting a communication route between saiddevice (controller) and said electronic devices; a disconnectiondetecting unit for detecting disconnection of said communication routedetected by said communication route detecting unit; and notifying unitfor notifying a user of a result of detection by said communicationroute detecting unit or by said disconnection detecting unit, saiddevice (controller) configured to send a flag-set command to one or moreelectronic devices connected along said communication route, in order toset a flag that is stored in each of said one or more electronicdevices, said device (controller) further configured to send aflag-reset command to said one or more electronic devices, in order toclear each said flag.
 18. The electronic device (controller) accordingto claim 17, wherein said disconnection detecting unit, when detectingdisconnection of one of said one or more electronic devices, notifiesthe user of said disconnection.
 19. The electronic device (controller)according to claim 17, wherein said electronic device (controller) holdsconnection information and continues communication when saidcommunication route is connected again within a predetermined time aftersaid disconnection detecting unit detects disconnection of one of saidone or more electronic devices.
 20. The electronic device (controller)according to claim 19, wherein said predetermined time is 30 seconds.21. The electronic device (controller) according to claim 19, whereinsaid device (controller) is configured so as not to assure communicationdata while said communication route is disconnected.
 22. The electronicdevice (controller) according to claim 17, wherein said device(controller) suppresses said notification to the user of a change of anetwork in case where said disconnection detecting unit detects nodisconnection from said network after a network reset event occurs dueto connection of a new electronic device or disconnection of anelectronic device from said network.
 23. An electronic device(controller) enabled to connect a different electronic device so as tocontrols said different electronic device remotely, said device(controller), comprising: a connection state storing unit for storingconnection information of said different electronic device connected toa network; a communication route detecting unit for detecting acommunication route between said device (controller) and said electronicdevices based on said connection information stored in said connectionstate storing unit; disconnection detecting unit for detectingdisconnection of said communication route detected by said communicationroute detection unit; and a notifying unit for notifying the user of aresult of detection by said communication route detecting unit or bysaid disconnection detecting unit, said device (controller) configuredto send a flag-set command to one or more electronic devices connectedalong said communication route, in order to set a flag that is stored ineach of said one or more electronic devices, said device (controller)further configured to send a flag-reset command to said one or moreelectronic devices, in order to clear each said flag.
 24. An electronicdevice comprising: a communication route flag data store having a firstvalue when said electronic device is connected along a communicationroute that is connected between a first electronic device and a secondelectronic device, and having a second value when said electronic deviceis not connected along a communication route that is connected between afirst electronic device and a second electronic device; and a displayunit for indicating the value that is stored in said communication routeflag data store, said electronic device configured to receive a flag-setcommand and a flag-reset command from a different electronic device(controller), to store said first value in said communication route flagdata store in response to receiving said flag-set command, and to storesaid second value in said communication route flag data store inresponse to receiving said flag-reset reset command.